How and why to transition from Microsoft AD CS to a private CA

Public key infrastructure (PKI) is the backbone of enterprise security, enabling encrypted communication, identity authentication, and data integrity across complex digital ecosystems. At the heart of PKI are certificate authorities (CAs), trusted entities that validate identities and issue SSL/TLS certificates to ensure secure operations. While public CAs dominate the landscape for external communication, many enterprises rely on Microsoft Active Directory Certificate Services (AD CS) to manage internal certificate management needs.

However, AD CS, while widely used, often falls short in today’s dynamic, hybrid, and cloud-centric environments. Its on-premises nature, limited flexibility, and reliance on manual processes can hinder scalability, integration, and compliance, leaving today’s complex enterprise environments vulnerable to security risks and operational inefficiencies.

Enter private CA solutions—modern platforms designed to overcome the limitations of services like Microsoft AD CS by offering advanced features such as automated certificate lifecycle management, integration across diverse environments, and the flexibility needed to adapt to evolving security requirements.

Among the most robust options available, Sectigo’s cloud-native private CA solution provides enterprises with a comprehensive suite of tools to secure their PKI ecosystems. With Sectigo, organizations can streamline operations, enhance scalability, and achieve crypto agility to prepare for future challenges. Whether transitioning away from AD CS or augmenting its capabilities, learn what enterprises stand to gain from Sectigo’s private CA solution and what it takes to achieve a smooth transition.

Challenges with Microsoft AD CS

Offering a free, built-in option for managing digital certificates, Microsoft AD CS may seem like the obvious solution for elevating security and authentication within the PKI ecosystem. Take a closer look, however, and the caveats become difficult to ignore:

• Manual tracking burdens: Because manual certificate management is so time-consuming, it can prevent busy IT professionals from addressing higher-priority tasks. Beyond escalating labor costs, manual tracking introduces significant risks due to its reliance on outdated methods like spreadsheets and fragmented workflows. Even the most skilled and dedicated professionals are not immune to errors, which can result in missed renewals, disorganized workflows, service outages, or costly non-compliance issues.

• Partial visibility and scaling issues: Visibility is a crucial component of certificate management, ensuring strong oversight and making it easier to respond promptly to emerging concerns. However, AD CS falls short in providing visibility beyond the Microsoft ecosystem, leaving gaps in certificate discovery, inventory, and lifecycle tracking. Its limited support for non-Microsoft systems further complicates scaling efforts across diverse enterprise environments.

• On-premises restrictions: As a strictly on-premises solution, AD CS relies on physical infrastructure, which can contribute to the previously discussed scaling concerns. On-premises setups can be restrictive for organizations that require hybrid or cloud-based solutions. Given the increased reliance on the cloud, AD CS simply is not equipped to meet the demands of today's dynamic digital ecosystem and with the rise of remote work, relying solely on an on-premises setup creates additional obstacles, such as ensuring secure access for distributed teams and managing certificates across diverse, geographically dispersed devices.

• Compliance and security risks: If AD CS is not properly configured or managed, organizations may become vulnerable to compliance concerns, including everything from improper key management to poor auditing or logging. This could be particularly troublesome for organizations that need to abide by strict standards such as HIPAA. Mismanagement can also prompt significant security gaps, as evidenced by the recently disclosed flaw in Microsoft Active Directory Certificate Services (CVE-2024-49019), which could allow attackers to escalate privileges and gain domain control. Jason Soroko, Senior Fellow at Sectigo, highlighted the danger of excessive enroll or auto-enroll permissions, which can make it difficult to track certificate issuance and prevent unauthorized access. These issues can expose sensitive data or cause disruptions from expired or mismanaged certificates.

It is important to consider the role of Network Device Enrollment Service (NDES) within the greater framework of AD CS, offering the chance to enroll various network devices via the Simple Certificate Enrollment Protocol (SCEP). NDES can be valuable but still faces scalability challenges and limiting reporting mechanisms.

The case for a private CA

A private CA is a customized solution that allows organizations to issue and manage digital certificates for tasks like securing internal communications, authenticating devices, and protecting sensitive data. Despite these benefits, many organizations have been slow to move beyond Microsoft AD CS because it still feels like the best or most cost-effective solution. Persistent misconceptions about private CA alternatives have prevented some enterprises from adopting this more flexible and crypto-agile solution. This could be an excellent time to shift towards a private CA, which offers many significant advantages:

• Enhanced security and control: With a private CA, fine-tuned control is not only possible but fully expected. Under this approach, tailored certificate policies can be established to meet unique security needs. This makes it possible to implement stronger cryptographic standards, stricter permissions, and custom certificate lifecycles, ensuring alignment with specific operational and compliance needs. Additionally, leveraging a modern PKI or Sectigo Certificate Manager (SCM) can better align your security practices with the NIST 2.0 Cybersecurity Framework, ensuring comprehensive protection and compliance.

• Cost and operational efficiency: At first glance, private CAs may seem more expensive than Microsoft AD CS, which is often regarded as a cost-effective solution. Take a closer look, however, and the long-term cost of maintaining AD CS no longer seems so impressive. For example: this approach calls for manual tracking which dramatically increases labor expenses and operational inefficiencies. Meanwhile, increased vulnerabilities (especially related to potential expiration) elevate the risk for unexpected downtime, which can lead to substantial financial and reputational losses. In contrast, private CAs offer streamlined operations and reduced security risk, delivering greater cost-efficiency over time.

• Flexibility and integration: AD CS may promise tight integration with the overarching Microsoft ecosystem, but a private CA can issue certificates across a wider range of platforms. What's more, private CAs promise seamless integrations with numerous applications, including non-Microsoft systems.

As a game changer in the private CA space, Sectigo promises all these advantages — and more. With a centralized dashboard, Sectigo provides unified visibility for both public and private certificates, while its lifecycle automation eliminates the complexities of certificate enrollment, renewal, and revocation. Additionally, its out-of-the-box AD CS integration makes Sectigo's private CA solution an excellent choice for augmenting existing AD CS frameworks.

Transitioning or augmenting AD CS with a private CA

Ready to make the switch to a private CA? Begin with an in-depth audit, which should reveal current weaknesses and opportunities for improvement. This should encompass a thorough inventory, revealing all existing digital certificates. Ideally, the discovery process will lead to a centralized inventory that reveals issuance and expiration dates, along with validation types and associated devices or users.

Take this opportunity to identify current gaps — and to determine how a private CA might address these. Key issues may involve:

• Missed expirations (attributed to manual workloads)

• Limited integrations with non-Microsoft systems

• Challenges tied to on-premises infrastructure, such as scalability limitations

• Compliance concerns (prompted by poor visibility or lackluster auditing).

Next, define your goals for phasing out AD CS while configuring and deploying the private CA. Start by determining the future role of AD CS: will it continue to support core Windows services, or will it be fully replaced by a private CA?

If AD CS remains valuable, augmentation may be the best path forward. This could mean implementing automated certificate lifecycle management (CLM) solutions — which Sectigo Certificate Manager offers — to address non-Microsoft use cases while retaining AD CS for core Windows services​​. That being said, a full transition to a private CA is worth considering, as this could dramatically improve flexibility and scalability while promoting seamless management across all platforms.

Once core objectives are established, it's time to proceed with a phased migration. Every phase should encompass clear milestones to ensure a smooth transition that avoids operational disruptions. This process should include the following steps:

• Set Timelines and Milestones: Create a clear timeline for each phase, starting with non-critical systems such as test environments and gradually progressing to mission-critical applications. Establish clear milestones for each phase to validate progress and ensure stakeholder alignment before moving forward.

• Implementation with Private CA Tools: Leverage tools provided by the private CA to facilitate discovery and migration. For example, SCM offers advanced certificate discovery capabilities to identify and manage all certificates—public, private, or AD CS-issued—ensuring nothing is overlooked. Gradually shift workloads to the private CA while maintaining business continuity. During the transition, automated lifecycle management workflows can run parallel to manual AD CS processes, reducing dependency on outdated methods. Over time, critical tasks and services can be fully redirected to the private CA to minimize risks and ensure uninterrupted operations.

• Integration and Training: Provide hands-on training for IT teams to familiarize them with the new system and the ease of automated certificate lifecycle management. Training ensures IT staff feel supported and confident in using the tools and workflows provided by the private CA. Sectigo’s support for phased rollouts prioritizes high-impact areas first, ensuring a smooth, efficient migration.

Addressing transition challenges

The transition to a private CA may be deemed necessary, but challenges are to be expected along the way. Many of these relate to legacy dependencies, which could make it difficult to stage a gradual transition. For example, legacy systems may not support modern CLM protocols such as Automated Certificate Management Environment protocol (ACME). Good news: Sectigo offers integration tools designed to help bridge the gap.

Regardless of legacy concerns, operational disruptions are possible — even when adopting a phased approach. Automated CLM can help avoid these issues by limiting the potential for expiration-prompted outages. Meanwhile, proactive workflows promote smooth transitions while real-time alerts ensure that any emerging issues are known and addressed before they have the chance to escalate.

While AD CS may initially seem like a cost-effective solution, its reliance on manual processes and limited automation creates challenges that can result in significant hidden costs during a transition. These inefficiencies often lead to increased labor expenses and operational risks, such as unplanned downtime from expired or mismanaged certificates. Such disruptions can compromise security and create financial strain, making the transition from AD CS to a private CA a necessity for organizations seeking long-term stability.

Sectigo’s private CA solution is designed to overcome these transition challenges while delivering substantial ROI. By offering modern and affordable solutions that are more cost-effective than previous private CA implementations, Sectigo makes advanced security accessible to enterprises. Automated CLM eliminates the reliance on time-consuming manual processes, reducing labor demands, and freeing up IT resources. Proactive management ensures compliance and prevents costly operational disruptions, making the transition smoother and more reliable for organizations of all sizes.

The future of PKI with Sectigo

Sectigo’s private CA solution will help you embrace the future of PKI. Sectigo provides excellent opportunities for addressing tomorrow's greatest security challenges, including:

• Crypto agility: New security threats are always around the corner, and unfortunately, these are arriving at an accelerating rate. Amid the chaos of this quickly changing digital landscape, crypto agility gives enterprises the ability to respond to new threats and new algorithms — but without disrupting operations. Sectigo promotes crypto agility by offering flexible key management solutions and automated certificate lifecycle management. Sectigo is also at the forefront of post-quantum cryptography, ensuring that, when the post-quantum era arrives, enterprises are ready to embrace quantum's opportunities without falling prey to potential quantum threats.

• Integrated private certificate management: Enterprise customers increasingly seek streamlined platforms that unify public CA, cloud, and private certificate management. A recent Altman Solon survey revealed that 76% of non-CLM adopters prefer combined public/private management, highlighting the need for integrated solutions. Sectigo's Private CA solution is uniquely positioned to address this by offering a centralized platform for managing both private and public certificates in one unified place.

• Streamlined compliance: Promising support for industry standards along with robust auditing capabilities, Sectigo equips organizations across numerous industries with the tools and support they need to maintain full compliance. Consolidated logs and dashboards streamline this effort, removing much of the hassle from an otherwise complex auditing process.

Moving forward with transitioning away from Microsoft AD CS

The shift away from Microsoft AD CS does not need to feel overwhelming. With a structured approach — and plenty of support from a trusted partner — a seamless transition is possible. Sectigo offers valuable tools and guidance during this process. Whether you're committed to making a full transition or augmenting an existing AD CS setup, Sectigo can provide assistance every step of the way.

Offering enterprise Private CA solutions, Sectigo promises cutting-edge strategies and certificate management via SCM, along with a unique opportunity for enterprises seeking to augment AD CS: tailored Microsoft Certificate Authority management. Reach out today to learn more about Sectigo's unique offerings.

Want to learn more? Get in touch to book a demo of Sectigo Certificate Manager!

Related posts:

Sectigo as your private Certificate Authority (CA)

Streamlining certificate management: The case for eliminating Microsoft Active Directory Certificate Services

Navigating the complexities: challenges in Microsoft AD CS and the role of automation